Recent advances using potent combinations of antiretroviral drugs have demonstrated marked reduction in HIV viral load as well as modest increases in CD4 lymphocyte numbers and growth velocity in HIV infected infants and children. The exact depth and reach of this reconstitution has yet to be characterized. We hypothesize that effective suppresion of viral burden using highly active antiretroviral therapy may have on HIV-infected children in the restoration of their impaired growth (body composition, energy balance, neuroendocrine axis, nutrient metabolism) and immune system (T cell phenotype and function, cytokine elaboration, delayed-type hypersensitivity reaction, thymic volume).